//
// Created by wangliewei on 2021/8/17.
//
/*注意，可能的逆序对的数量的上限是10的9次方数量级的，可根据N的最大值推算出来
*/
#include<iostream>
using namespace std;

const int N = 100010;
int q[N], tmp[N];
typedef long long LL;

LL merge_sort(int l, int r) {
    if (l == r) return 0;

    int mid = l + r >> 1;
    LL res = merge_sort(l, mid) + merge_sort(mid + 1, r);

    //归并的过程
    int i = l, j = mid + 1, k = 0;
    while(i <= mid && j <= r) {
        if (q[i] <= q[j]) tmp[k++] = q[i++];
        else{
            tmp[k++] = q[j++];
            res += mid - i + 1;
        }
    }
    //扫尾
    while (i <= mid ) tmp[k++] = q[i++];
    while (j <= r) tmp[k++] = q[j++];

    //物归原主
    for (int i = l, j = 0; i <= r; i ++, j++) {
        q[i] = tmp[j];
    }
    return res;
}

int main () {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) scanf("%d", &q[i]);

    cout << merge_sort(0, n - 1) << endl;


    return 0;
}
